Damped valve train system

ABSTRACT

A valve train having a damping means acting on one of the valve train elements prior to valve closing to reduce &#39;&#39;&#39;&#39;valve toss&#39;&#39;&#39;&#39; or &#39;&#39;&#39;&#39;bounce&#39;&#39;&#39;&#39; characteristically present at exceptionally high engine speeds. The damping means may comprise a hydraulic or pneumatic device having a collapsible chamber from which flow is restricted and which reduces the velocity of the valve train elements just prior to valve closing.

United States Patent Repko et al.

[ 1 July 25,1972

[54] DAMPED VALVE TRAIN SYSTEM [72] Inventors: Louis L. Repko, Detroit;Richard C. Ronzi, Southfield, both of Mich.

[73] Assignee: Ford Motor Company, Dearborn, Mich.

[22] Filed: Dec. 4, 1970 [21] Appl. No.: 95,220

[52] U.S. Cl ..l23/90.47, 123/9049, 123/9066 [51] lnt.Cl ..F0ll 1/16,F011 1/18 [58] Field of Search ..123/90.47, 90.49. 9066 [56] ReferencesCited UNITED STATES PATENTS 3,563,217 2/1971 Bartels ..l23/90.662,552,006 5/1951 Gill, Jr. ..123/90.49 X

2,607,330 8/1952 Hartung ..123/90.47 2,669,228 2/1954 Bergmann..123/90.47 2,672,134 3/l954 Hunt ..l23/90.47 3,024,775 3/1962 Wuest123/9047 X Primary Examiner-Al Lawrence Smith Attorney-John R. Faulknerand Roger E. Erickson [5 7] ABSTRACT A valve train having a dampingmeans acting on one of the valve train elements prior to valve closingto reduce valve toss" or bounce" characteristically present atexceptionally high engine speeds. The damping means may comprise ahydraulic or pneumatic device having a collapsible chamber from whichflow is restricted and which reduces the velocity 0 the valve trainelements just prior to valve closing. I

14 Claims, 2 Drawing Figures Patented July 25, 1972 2 Sheets-Sheet 1PIC-3.1

s &Q% R o 0 2 E KW w m w? w a m ADQE 5 5% DAMPED VALVE TRAIN SYSTEMBACKGROUND OF THE INVENTION A principal factor limiting the increase ofinternal combustion engine output by extending the range of engine RPMsis a phenomenon called valve bounce" or valve toss", which results whenthe intake valve closing velocities are of a magnitude great enough tocause undesirable reopenings of the individual valve elements. Thesereopenings are caused by the dynamics of the valve train at extremelyhigh rotational speeds rather than in response to the engine camshaft.

This invention provides a valve train construction in which valve bounceis substantially eliminated. Further, it provides a valve trainconstruction in which the closing velocities of the valves are reducedin magnitude just prior to closing impact. The invention also provides avalve train construction in which valve and valve spring life aresignificantly increased. Still further, this invention provides a dampedvalve train construction which may be incorporated into conventionalinternal combustion engines and which may be economically produced.

SUMMARY OF THE INVENTION A damped valve constructed in accordance withthis invention comprises elements including a valve reciprocably mountedwithin an engine cylinder head that opens and closes a port formedwithin the cylinder head, a rocker arm pivotally mounted to the cylinderhead and engagable with the valve, and a push rod engagable with therocker arm to transmit motion thereto, a spring biasing the valve towarda closed position, and damping means opposing the spring and engagablewith one of the above valve train elements to retard closing and toreduce the valve closing velocity.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a transverse cross sectionalview of a cylinder head and valve train illustrating a bolt-on typedamper mechanism engagable with the rocker arm.

FIG. 2 is a transverse cross sectional view of a cylinder head and valvetrain showing an in-head mounted damper mechanism engagable with therocker arm.

DESCRIPTION OF A PREFERRED EMBODIMENT FIG. 1 of the drawings shows apreferred embodiment of the invention having a cylinder head 11 formedwith an intake passage 12 leading from the intake manifold (not shown)to a combustion chamber (not shown). A poppet valve 13 is slidablymounted within a bore 14 formed within the cylinder head. The valve isaxially movable to open and close an intake valve port 16. Compressedbetween the cylinder head at 17 and a retainer 18 is spring 19 whichurges the valve toward a closed position. The retainer is secured to theend of the valve stem by a pair of locks 21 that engage a groove 22 inthe end of the valve 13.

A rocker arm 23 is connected to the cylinder head 11 by stud 24. Therocker arm has a concave cylindrical surface 27 on a fulcrum seat 28,retained to stud 24 by nut 29. The rocker arm surface 26 and the fulcrumseat surface 27 determine an axis about which the rocker arm pivots. Theend of the rocker arm opposite of the valve engages a push rod 31 whichtransmits motion from the engine camshaft and a tappet (both not shown)to the rocker arm. The description to this point describes a generallyconventional internal combustion engine construction.

A damper or dashpot mechanism 32 is secured to the cylinder head 11 bycapscrew 33. The damper 32 includes an arm 34 positioned adjacent therocker arm 23 and having a blind bore 36 coaxial with the valve 13. Apassage 37 is drilled in the arm which communicates with the pressurizedlubrication circuit of the engine and provides oil to the bore 36. Agenerally hollow piston 38 is slidably and sealingly received withinbore 36 and forms, in cooperation with the bore, a variable volumechamber 39. Compression spring 41 biases the piston 38 toward itsmaximum extended position in which it abuts retaining ring 42.

A one-way check valve assembly 42 permits the flow of oil from theinternal lubrication passage 37 through port or passage 43 into chamber39 when the chamber is not under compression. The valve assemblyincludes a perforated cage 45 which retains a ball 44 adjacent port 43.Upon initial compression of the chamber, ball 44 seats in port 43 toclose valve 42. Further compression forces oil in a relativelyrestricted flow through a vent passage 46. A small clearance may beprovided between piston 38 and bore 36 permitting a restricted flow ofoil to be forced between the piston and bore during chamber compression.Piston 38 includes a protruding end 47 adjacent the rocker arm 23 whichis spaced from the rocker arm at all times except for a short time priorto and after closure of valve 13.

The valve train damper described above functions to prevent or reducevalve bounce of valve 13 immediately after the normal valve closing.Toward the end of the valve closing stroke, portion 48 of the rockerarm'engages the end 47 of piston 38. Chamber 39 is then placed undercompression, check valve 42 closes and oil is forced from the chamberthrough the passage 46 and/or between piston 38 and bore 36 in arestricted and controlled fashion. This controlled collapse of chamber39 introduces a damping action into the valve train movement and reducesthe closing velocity and impact of the valve 13. As the valve 13 beginsto open, the check valve 42 opens and the damper mechanism 32 has nofurther damping effect on the valve train elements. Spring 41 causes thepiston 38 to extend against ring 42 and to draw oil from the internalpassage 37 past the check valve 42 into the chamber 39. The piston isthen positioned and ready for its next damping function.

An alternate embodiment of the invention is shown in FIG. 2. Only thosedetails difierent from FIG. 1 will be described. A damper assembly isreferred to generally by number 56 and is formed in part by the cylinderhead 11. Rocker arm 57 extends past the normal push rod socket 58 toform a portion 59 engagable with an element of the damper assembly 56.

The damper assembly 56 comprises a blind bore 61 formed within thecylinder head 11 having an axis substantially parallel to that of pushrod 31. A generally hollow piston 62 is slidably and sealingly receivedwithin bore 61 and forms in cooperation with the bore, a variable volumechamber 64. Compression spring 66 biases the piston 62 toward itsmaximum extended position in which it abuts retaining ring 67.

A one-way valve or check valve assembly 68 permits the flow of oil frominternal lubrication passage'69 through port or passage 71 into chamber64 when the chamber is not under compression. The valve assemblyincludes a perforated cage 72 which retains a ball 73 adjacent port 71.Upon initial compression of the chamber, the ball seats in the port toclose check valve 68. Further compression forces oil in a relativelyrestricted flow through passage 74. A small amount of oil may also forcebetween the piston 62 and bore 61 during chamber compression. Piston 62includes a protruding end 76 adjacent the rocker arm portion 59 which isspaced from the rocker arm at all times except just prior to and justafter closure of valve 13.

In function the embodiments of FIGS. 1 and 2 are substantiallyidentical. Portion 59 of rocker arm 57 engages end 76 of piston 62 nearthe end of the closing stroke of valve 13. Chamber 64 is then compressedcausing ball 73 of valve 68 to close port 71. Oil from chamber 64 isforced through restricted passage 74 permitting further collapse of thechamber and introducing a damping effect to the valve train movement.Such damping reduces the closing velocity of valve 13 to eliminate orreduce valve bounce.

We claim:

1. In an internal combustion engine including a cylinder head and a portformed within said cylinder head,

a valve train comprising elements including a poppet valve reciprocablymounted within said cylinderv head to open and close said port,

a rocker arm pivotally mounted to said cylinder head and engaging saidvalve, and

a push rod engagable with said rocker arm to transmit motion thereto,

spring means biasing said valve toward a closed position,

damping means opposing said spring means and engagable with one of saidvalve train elements to retard valve closing and reduce valve closingvelocity,

said damping means being disengagable with said one valve train elementduring the first portion of the valve closing stroke and engagable withsaid one element during the latter portion of the valve closing stroke.

2. A valve train according to claim 1 wherein:

said-damping means comprises a hydraulic device having a variable volumechamber,

means to restrict collapse of said chamber during the valve closingstroke and to permit relatively unrestricted expansion of said chamberduring the valve opening stroke.

3. A valve train according to claim 1 and including:

said damping means comprising a hydraulic device having a variablevolume chamber,

first passage means leading from said chamber permitting restricted flowduring chamber collapse,

second passage means opening into said chamber,

check valve means to permit relatively unrestricted flow into saidchamber through said second passage.-

4. A valve train according to claim 1 and including:

said damping means being fixed relative to said cylinder head andincluding a portion having a bore formed therein,

a piston slidably and sealingly received within said bore,

said piston and said bore forming a variable volume chamber,

means biasing said piston in a direction tending to maximize the volumeof said chamber,

a first passage leading from said chamber to permit a restricted flow ofhydraulic fluid from said chamber,

a second passage leading to said chamber to permit a relativelyunrestricted flow of hydraulic fluid into said chamber,

check valve means to substantially prevent flow from said chamberthrough said second passage when the volume of said chamber isdecreasing.

5. A valve train according to claim 1 and including:

said damping means being fixed relative to said cylinder head andincluding a portion having a bore formed therein,

a piston slidably and sealingly received within said bore,

said piston and said bore forming a variable volume hydraulic chamber,

first means biasing said piston in a direction tending to maximize thevolume of said chamber,

second means restricting and controlling collapse of said chamber andpermitting relatively unrestricted expansion of said chamber from acollapsed condition.

6. A valve train according to claim 1 and including:

said dampingfmeans engaging said rocker arm during at least the latterportion of the closing stroke of said firstmentioned valve.

7. A valve train according to claim 1 and including:

said damping means being fixed relative to said cylinder head andincluding a portion having a bore formed therein,

a piston slidably received within said bore,

said piston and bore forming a variable volume chamber,

means biasing said piston in a direction tending to maximize the volumeof said chamber,

passage means leading to said chamber to permit a flow of hydraulicfluid intosaid chamber,

check valve means to substantially prevent flow from said chamberthrough said passage means when the volume of said chamber isdecreasing,

said piston having a predetermined clearance with said bore to permitrestricted flow from said chamber between said piston and said bore whenthe volume of said chamber is decreasing.

8. In an internal combustion engine including a cylinder head and a portformed within said cylinder head,

a valve train comprising elements including a poppet valve reciprocablymounted within said cylinder head to open and close said port,

a rocker arm pivotally mounted to said cylinder head and engaging saidvalve, and

means engagable with said rocker arm to impart motion thereto,

spring means biasing said valve toward a closed position,

damping means opposing said spring means and engagable with one of saidvalve train elements to retard valve closing and reduce valve closingvelocity,

said damping means being disengagable from said one valve train elementduring the first portion of the valve closing stroke and engagable withsaid one element during the latter portion of the valve closing stroke.

9. A valve train according to claim 8 wherein:

said damping means comprises a hydraulic device having a variable volumechamber,

means to restrict collapse of said chamber during the valve closingstroke and to permit relatively unrestricted expansion of said chamberduring the valve opening stroke.

10. A valve train according to claim 8 and including:

said damping means comprising a hydraulic device having a variablevolume chamber,

first passage means leading from said chamber permitting restricted flowduring chamber collapse,

second passage means opening into said chamber,

check valve means to permit relatively unrestricted flow into saidchamber through said second passage.

11. A valve train according to claim 8 and including:

said damping means being fixed relative to said cylinder head andincluding a portion having a bore formed therein,

a piston slidably and sealingly received within said bore,

said piston and said bore forming a variable volume chamber,

means biasing said piston in a direction tending to maximize the volumeof said chamber,

a first passage leading from said chamber to permit a restricted flow ofhydraulic fluid from said chamber,

a second passage leading to said chamber to permit a relativelyunrestricted flow of hydraulic fluid into said chamber,

check valve means to substantially prevent flow from said chamberthrough said second passage when the volume of said chamber isdecreasing.

12. A valve train according to claim 8 and including:

said damping means being fixed relative to said cylinder head andincluding a portion having a bore formed therein,

a piston slidably and sealingly received within said bore,

said piston and said bore forming a variable volumehydraulic chamber,

first means biasing said piston in a direction tending to maximize thevolume of said chamber,

second means restricting and controlling collapse of said chamber andpermitting relatively unrestricted expansion of said chamber from acollapsed condition.

13. A valve train according to claim 12 and including:

said damping means engaging said rocker arm during at least the latterportion of the closing stroke of said firstmentioned valve.

14. A valve train according to claim 8 and including:

said damping means being fixed relative to said cylinder head andincluding a portion having a bore formed therein,

a piston slidably received within said bore,

said piston and bore forming a variable volume chamber,

said chamber is decreasing, said piston having a predetermined clearancewith said bore to permit restricted flow from said chamber between saidpiston and said bore when the volume of said chamber is decreasing.

1. In an internal combustion engine including a cylinder head and a portformed within said cylinder head, a valve train comprising elementsincluding a poppet valve reciprocably mounted within said cylinder headto open and close said port, a rocker arm pivotally mounted to saidcylinder head and engaging said valve, and a push rod engagable withsaid rocker arm to transmit motion thereto, spring means biasing saidvalve toward a closed position, damping means opposing said spring meansand engagable with one of said valve train elements to retard valveclosing and reduce valve closing velocity, said damping means beingdisengagable with said one valve train element during the first portionof the valve closing stroke and engagable with said one element duringthe latter portion of the valve closing stroke.
 2. A valve trainaccording to claim 1 wherein: said damping means comprises a hydraulicdevice having a variable volume chamber, means to restrict collapse ofsaid chamber during the valve closing stroke and to permit relativelyunrestricted expansion of said chamber during the valve opening stroke.3. A valve train according to claim 1 and including: said damping meanscomprising a hydraulic device having a variable volume chamber, firstpassage means leading from said chamber permitting restricted flowduring chamber collapse, second passage means opening into said chamber,check valve means to permit relatively unrestricted flow into saidchamber through said second passage.
 4. A valve train according to claim1 and including: said damping means being fixed relative to saidcylinder head and including a portion having a bore formed therein, apiston slidably and sealingly received within said bore, said piston andsaid bore forming a variable volume chamber, means biasing said pistonin a direction tending to maximize the volume of said chamber, a firstpassage leading from said chamber to permit a restricted flow ofhydraulic fluid from said chamber, a second passage leading to saidchamber to permit a relatively unrestricted flow of hydraulic fluid intosaid chamber, check valve means to substantially prevent flow from saidchamber through said second passage when the volume of said chamber isdecreasing.
 5. A valve train according to claim 1 and including: saiddamping means being fixed relative to said cylinder head and including aportion having a bore formed therein, a piston slidably and sealinglyreceived within said bore, said piston and said bore forming a variablevolume hydraulic chamber, first means biasing said piston in a directiontending to maximize the volume of said chamber, second means restrictingand controlling collapse of said chamber and permitting relativelyunrestricted expansion of said chamber from a collapsed condition.
 6. Avalve train according to claim 1 and including: said damping meansengaging said rocker arm during at least the latter portion of theclosing stroke of said first-mentioned valve.
 7. A valve train accordingto claim 1 and including: said damping means being fiXed relative tosaid cylinder head and including a portion having a bore formed therein,a piston slidably received within said bore, said piston and boreforming a variable volume chamber, means biasing said piston in adirection tending to maximize the volume of said chamber, passage meansleading to said chamber to permit a flow of hydraulic fluid into saidchamber, check valve means to substantially prevent flow from saidchamber through said passage means when the volume of said chamber isdecreasing, said piston having a predetermined clearance with said boreto permit restricted flow from said chamber between said piston and saidbore when the volume of said chamber is decreasing.
 8. In an internalcombustion engine including a cylinder head and a port formed withinsaid cylinder head, a valve train comprising elements including a poppetvalve reciprocably mounted within said cylinder head to open and closesaid port, a rocker arm pivotally mounted to said cylinder head andengaging said valve, and means engagable with said rocker arm to impartmotion thereto, spring means biasing said valve toward a closedposition, damping means opposing said spring means and engagable withone of said valve train elements to retard valve closing and reducevalve closing velocity, said damping means being disengagable from saidone valve train element during the first portion of the valve closingstroke and engagable with said one element during the latter portion ofthe valve closing stroke.
 9. A valve train according to claim 8 wherein:said damping means comprises a hydraulic device having a variable volumechamber, means to restrict collapse of said chamber during the valveclosing stroke and to permit relatively unrestricted expansion of saidchamber during the valve opening stroke.
 10. A valve train according toclaim 8 and including: said damping means comprising a hydraulic devicehaving a variable volume chamber, first passage means leading from saidchamber permitting restricted flow during chamber collapse, secondpassage means opening into said chamber, check valve means to permitrelatively unrestricted flow into said chamber through said secondpassage.
 11. A valve train according to claim 8 and including: saiddamping means being fixed relative to said cylinder head and including aportion having a bore formed therein, a piston slidably and sealinglyreceived within said bore, said piston and said bore forming a variablevolume chamber, means biasing said piston in a direction tending tomaximize the volume of said chamber, a first passage leading from saidchamber to permit a restricted flow of hydraulic fluid from saidchamber, a second passage leading to said chamber to permit a relativelyunrestricted flow of hydraulic fluid into said chamber, check valvemeans to substantially prevent flow from said chamber through saidsecond passage when the volume of said chamber is decreasing.
 12. Avalve train according to claim 8 and including: said damping means beingfixed relative to said cylinder head and including a portion having abore formed therein, a piston slidably and sealingly received withinsaid bore, said piston and said bore forming a variable volume hydraulicchamber, first means biasing said piston in a direction tending tomaximize the volume of said chamber, second means restricting andcontrolling collapse of said chamber and permitting relativelyunrestricted expansion of said chamber from a collapsed condition.
 13. Avalve train according to claim 12 and including: said damping meansengaging said rocker arm during at least the latter portion of theclosing stroke of said first-mentioned valve.
 14. A valve trainaccording to claim 8 and including: said damping means being fixedrelative to said cylinder head and including a portion having a boreformed therein, a piston slidably received within said bore, said pistonand bore forming a variable volume chamber, means biasing said piston ina direction tending to maximize the volume of said chamber, passagemeans leading to said chamber to permit a flow of hydraulic fluid intosaid chamber, check valve means to substantially prevent flow from saidchamber through said passage means when the volume of said chamber isdecreasing, said piston having a predetermined clearance with said boreto permit restricted flow from said chamber between said piston and saidbore when the volume of said chamber is decreasing.